Ixodidae Explained

The Ixodidae are the family of hard ticks or scale ticks,^[1] one of the three families of ticks, consisting of over 700 species. They are known as 'hard ticks' because they have a scutum or hard shield, which the other major family of ticks, the 'soft ticks' (Argasidae), lack. They are ectoparasites of a wide range of host species, and some are vectors of pathogens that can cause human disease.

Description

They are distinguished from the Argasidae by the presence of a scutum.^[2] In both the nymph and the adult, a prominent gnathosoma (or capitulum, mouth and feeding parts) projects forward from the animal's body; in the Argasidae, conversely, the gnathosoma is concealed beneath the body.

They differ, too, in their lifecycle; Ixodidae that attach to a host bite painlessly and are generally unnoticed, and they remain in place until they engorge and are ready to change their skin; this process may take days or weeks. Some species drop off the host to moult in a safe place, whereas others remain on the same host and only drop off once they are ready to lay their eggs.

Classification

There are 702 species in 14 genera.^[3] The family contains these genera:^[3]

• Africaniella – two species
• Amblyomma – 130 species (includes some of Aponomma)
• Anomalohimalaya – three species
• Archaeocroton – one species
• Bothriocroton – seven species
• Cosmiomma – one species
• Cornupalpatum – one species
• Compluriscutula – one species
• Dermacentor – 34 species (includes Anocentor)
• Haemaphysalis – 166 species
• Hyalomma – 27 species
• Ixodes – 246 species
• Margaropus – three species
• Nosomma – two species
• Rhipicentor – two species
• Rhipicephalus – 82 species (includes Boophilus)
• Robertsicus – one species

Fossil genera

• †Compluriscutula Poinar and Buckley 2008 Burmese amber, Myanmar, Cenomanian
• †Cornupalpatum Poinar and Brown 2003 Burmese amber, Myanmar, Cenomanian

Medical importance

See also: Tick-borne disease.

Many hard ticks are of considerable medical importance, acting as vectors of diseases caused by bacteria, protozoa, and viruses, such as Rickettsia and Borrelia.^[2] Other tick-borne diseases include Lyme disease, babesiosis, ehrlichiosis, Rocky Mountain spotted fever, anaplasmosis, Southern tick-associated rash illness, tick-borne relapsing fever, tularemia, Colorado tick fever, Powassan encephalitis, and Q fever.^[4]

See also

• Ticks of domestic animals

Notes and References

1. Web site: . Ixodidae. NCBI taxonomy. National Center for Biotechnology Information. 28 September 2017. Bethesda, MD. en. Lineage(full) cellular organisms; Eukaryota; Opisthokonta; Metazoa; Eumetazoa; Bilateria; Protostomia; Ecdysozoa; Panarthropoda; Arthropoda; Chelicerata; Arachnida; Acari; Parasitiformes; Ixodida; Ixodoidea. https://web.archive.org/web/20180514165123/https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=6939. 14 May 2018. live.
2. Book: Francis E. G. Cox . 1993 . Modern parasitology: a textbook of parasitology . 2nd . . 978-0-632-02585-5 . D. H. Molyneux . Vectors . 53–74 . https://books.google.com/books?id=jj18axV3TTAC&pg=PA6 . 2016-11-06 . https://web.archive.org/web/20170215154441/https://books.google.com/books?id=jj18axV3TTAC&pg=PA6 . 2017-02-15 . live .
3. Alberto A. Guglielmone . Richard G. Robbing . Dmitry A. Apanaskevich . Trevor N. Petney . Agustín Estrada-Peña . Ivan G. Horak . Renfu Shao . Stephen C. Barker . 2010 . The Argasidae, Ixodidae and Nuttalliellidae (Acari: Ixodida) of the world: a list of valid species names . . 2528 . 1–28 . 10.11646/zootaxa.2528.1.1 . 11336/97869 . 2015-06-28 . https://web.archive.org/web/20190724235109/https://www.mapress.com/zootaxa/2010/f/z02528p028f.pdf . 2019-07-24 . live .
4. Web site: CDC - Tick-Borne Diseases - NIOSH Workplace Safety and Health Topic. 2018-11-14. www.cdc.gov. en-us. 2019-07-01. https://web.archive.org/web/20190701052949/https://www.cdc.gov/niosh/topics/tick-borne/default.html. 2019-07-01. live.